Magnetic resonance imaging apparatus, hyperpolarization signal obtaining method, and non-volatile computer-readable storage medium storing therein hyperpolarization signal obtaining program

Abstract

A magnetic resonance imaging apparatus includes sequence controlling circuitry configured: to obtain, during a time period after excitation of a first nuclide in a hyperpolarized state but no later than before obtainment of a first magnetic resonance signal from the first nuclide, a second magnetic resonance signal from a second nuclide that is different from the first nuclide and is in a non-hyperpolarized state, by exciting the second nuclide; and to control each of gradient magnetic field waveforms so as to cause both a first sum indicating a sum of application amounts of a gradient magnetic field related to the excitation of the second nuclide and a second sum indicating a sum of application amounts of a gradient magnetic field related to the obtainment of the second magnetic resonance signal to be close to zero, no later than before the obtainment of the first magnetic resonance signal.

What is claimed is: 
     
       1. A magnetic resonance imaging apparatus comprising sequence controlling circuitry configured:
 to obtain, during a time period after excitation of a first nuclide in a hyperpolarized state but no later than before obtainment of a first magnetic resonance signal from the first nuclide, a second magnetic resonance signal from a second nuclide that is different from the first nuclide and is in a non-hyperpolarized state, by exciting the second nuclide; and 
 to control each of gradient magnetic field waveforms so as to cause both a first sum indicating a sum of application amounts of a gradient magnetic field related to the excitation of the second nuclide and a second sum indicating a sum of application amounts of a gradient magnetic field related to the obtainment of the second magnetic resonance signal to be close to zero, no later than before the obtainment of the first magnetic resonance signal. 
 
     
     
       2. The magnetic resonance imaging apparatus according to  claim 1 , wherein
 a plurality radio frequency (RF) pulses applied to the first nuclide include a flip pulse and a plurality of flop pulses, and 
 the sequence controlling circuitry is configured to obtain the second magnetic resonance signal in a time period between two adjacent flop pulses among the plurality of flop pulses. 
 
     
     
       3. The magnetic resonance imaging apparatus according to  claim 2 , wherein the sequence controlling circuitry is configured to excite the second nuclide and to obtain the second magnetic resonance signal in a time period between two applications of a gradient magnetic field related to the application of the plurality of flop pulses. 
     
     
       4. The magnetic resonance imaging apparatus according to  claim 2 , wherein the sequence controlling circuitry is configured to obtain the first magnetic resonance signal, after one of the plurality of flop pulses that is applied after the obtainment of the second magnetic resonance signal. 
     
     
       5. The magnetic resonance imaging apparatus according to  claim 2 , wherein the sequence controlling circuitry is configured to apply an RF pulse related to the excitation of the second nuclide, during a time period after the application of the flip pulse but no later than before the application of the flop pulses. 
     
     
       6. The magnetic resonance imaging apparatus according to  claim 2 , wherein the sequence controlling circuitry is configured to cause the first sum and the second sum to be close to zero no later than before the application of a last one of the plurality of flop pulses. 
     
     
       7. The magnetic resonance imaging apparatus according to  claim 1 , wherein the first sum and the second sum are both zero. 
     
     
       8. The magnetic resonance imaging apparatus according to  claim 1 , wherein the following do not overlap with one another: an application time period of a gradient magnetic field at the time of exciting the first nuclide; an application time period of a gradient magnetic field related to the obtainment of the first magnetic resonance signal; an application time period of the gradient magnetic field at the time of exciting the second nuclide; and an application time period of the gradient magnetic field related to the obtainment of the second magnetic resonance signal. 
     
     
       9. The magnetic resonance imaging apparatus according to  claim 1 , wherein the sequence controlling circuitry is configured to obtain the second magnetic resonance signal multiple times. 
     
     
       10. The magnetic resonance imaging apparatus according to  claim 1 , wherein the sequence controlling circuitry is configured to simultaneously carry out the excitation of the first nuclide and the excitation of the second nuclide. 
     
     
       11. The magnetic resonance imaging apparatus according to  claim 1 , wherein, after the obtainment of the first magnetic resonance signal, the sequence controlling circuitry is configured to generate a spoiler pulse related to the obtainment of the second magnetic resonance signal. 
     
     
       12. The magnetic resonance imaging apparatus according to  claim 1 , wherein the second nuclide is protons. 
     
     
       13. A hyperpolarization signal obtaining method comprising:
 exciting a first nuclide in a hyperpolarized state; 
 exciting a second nuclide that is different from the first nuclide and is in a non-hyperpolarized state, during a time period no later than before obtainment of a first magnetic resonance signal from the first nuclide; 
 causing a first sum indicating a sum of application amounts of a gradient magnetic field related to the excitation of the second nuclide to be close to zero, no later than before the obtainment of the first magnetic resonance signal; 
 obtaining a second magnetic resonance signal from the second nuclide; 
 causing a second sum indicating a sum of application amounts of a gradient magnetic field related to the obtainment of the second magnetic resonance signal to be close to zero, no later than before the obtainment of the first magnetic resonance signal; and 
 obtaining the first magnetic resonance signal after the second sum is caused to be close to zero. 
 
     
     
       14. A non-volatile computer-readable storage medium storing therein a hyperpolarization signal obtaining program that causes a computer to realize:
 controlling transmission circuitry so as to excite a first nuclide in a hyperpolarized state; 
 controlling the transmission circuitry so as to excite a second nuclide that is different from the first nuclide and is in a non-hyperpolarized state, during a time period no later than before obtainment of a first magnetic resonance signal from the first nuclide; 
 controlling a gradient power source so as to cause a first sum indicating a sum of application amounts of a gradient magnetic field related to the excitation of the second nuclide to be close to zero, no later than before the obtainment of the first magnetic resonance signal; 
 controlling the gradient power source so as to obtain a second magnetic resonance signal from the second nuclide; 
 controlling the gradient power source so as to cause a second sum indicating a sum of application amounts of a gradient magnetic field related to the obtainment of the second magnetic resonance signal to be close to zero, no later than before the obtainment of the first magnetic resonance signal; and 
 controlling the gradient power source so as to obtain the first magnetic resonance signal after the second sum is caused to be close to zero.